Field of the Invention
This invention relates to controls for controlling the speed of an assorting carrier and for issuing synchronizing signals to determine the position of an assorting carrier in the goods assorting apparatus.
In the goods assorting apparatus, it is required to control an assorting carrier so as to be at a specified speed and to confirm that an assorting carrier has reached the specified assorting chute so as to assort goods loaded on the assorting carrier to the desired destination (assorting chute). For this purpose, a means of detecting the speed of an assorting carrier and issuing synchronizing signals corresponding to the movement of an assorting carrier for identifying the position of the assorting carrier which is moving was required. In the conventional goods assorting apparatus, a means of detecting the rotational speed of a driving mechanism for the assorting carrier in relation to the axis of rotation is provided for detecting the speed of the assorting carrier and for issuing synchronizing signals.
However, if the driving system for the assorting carrier is a linear motor driving system, rotation of a driving part does not exist and therefore it is impossible to detect the speed and issue synchronizing signals by detecting the rotation of the axis of rotation.
In view of the above, the Japanese Laid-Open Patent Application No. 64-81602, for example, disclosed the method whereby a reaction plate provided for an assorting carrier is detected by two sets of photoelectric switch for detecting the speed and issuing synchronizing signals.
In the above method, a detection signal of pulse waveform is issued in correspondence to the movement of a reaction plate; pulse synchronizing between ON and OFF of the detection signal is determined; an interpolation pulse is formed by carrying out pulse interpolating and is fractionized; information is coded and synchronizing signals are issued. In this method, however, the interpolation pulse is formed on the assumption that the moving speed of the assorting carrier does not change or remains almost the same during the time of the next pulse period. Therefore, in the case where the speed of the assorting carrier has changed, the time of the pulse period changes and consequently the interpolation pulse lags and synchronizing signals cannot be issued timely. Thus, it is difficult to follow the change of speed of the assorting carrier, with the result that the assorting control cannot be done accurately.
The present invention has for its object to change the pulse signal according to any change of the speed of the assorting carrier and to obtain synchronizing signals for improving the precision of assorting operations.
In order to attain the above object, the main point of the present invention is that the moving state of an assorting carrier by the linear motor driving system is detected by a group of photoelectric switches (16 pcs.) which are arranged at regular intervals in each section of a reaction plate for detection of the speed of the assorting carrier and issuance of synchronizing signals, whereby goods are assorted accurately to the specified assorting destination.